1. Field of Invention
The present invention relates generally to a label printer for printing labels affixed to a web liner, and relates more particularly to a label printer having a label peeling mechanism for peeling labels from a web liner, and to a control method for this label printer.
2. Description of Related Art
Label printers are used for printing labels with such information as a product name, price, and product code (barcode). The labels are thereafter affixed to products.
In the back room of a store, for example, the label printer is typically placed on a work-table to print labels, and as the labels are affixed to the products as they are printed and peeled from a web liner. Label printers are also used to batch print multiple labels, which are then taken to a separate location, such as the warehouse where the products are stored, and the labels are applied to the individual products.
In the former application, a label peeling mechanism is preferably used to automatically peel the labels one by one from the web liner as the labels are printed.
A label printer with such a label peeling mechanism is taught in Japanese Unexamined Patent Appl. Pub. H8-295323 (corresponding to U.S. Pat. No. 5,980,138), for example. This label printer stores a roll of label paper having labels affixed at a constant interval to the surface of a continuous web liner in a storage compartment inside the printer. The leading end of the roll paper is fed between the print head and platen roller so that the roll paper can be advanced and printed, and is then passed outside of the printer. The web liner (or simply web) held between and conveyed by the drive platen roller and a peeling roller (pinch roller) that rotates following the platen roller.
This printer can be set to operate in a non-peeling mode (continuous printing mode) in which the label peeling mechanism is not used or a peeling mode in which the label peeling mechanism is used. The non-peeling mode is set by passing the leading end of the roll paper (labels affixed to a web liner) through the label discharge opening (label dispenser opening) of the label peeling mechanism, and enables printing and outputting multiple labels intact on the web. The peeling mode is set by threading the leading end of the roll paper around a curved portion of the label peeling mechanism before passing the end outside the printer, thus enabling the label peeling mechanism to peel and dispense the printed labels one by one from the web as the labels are printed.
Whether the label peeling mechanism is used or not is selected by the operator opening the peeler cover, which is part of the peeling mechanism, and passing or not passing the leading end of the roll paper out through the label discharge opening (label dispenser opening).
To set the label paper 58 (roll paper having labels affixed at a constant interval to a web liner 59) to use the peeling mode as shown in FIG. 12A, a number of labels must first be peeled from the leading end of the label paper 58 so that only the web liner 59 is left. When the label peeling mechanism is used, the web liner 59 is held and conveyed between the platen roller 50 and peeling roller 50a after the labels are peeled. This is because the paper transportation load is high around the web-bending guide 53 of the label peeling mechanism, and if thick paper, such as label paper 58 having the labels intact on the web liner 59, is fed between the platen roller 50 and peeling roller 50a, the transportation load is even greater and feeding the label paper may not be possible. In addition, the labels tend to separate from the web and stick to the platen roller 50 or peeling roller 50a, and paper jams thus occur easily. As a result, a number of labels must be removed from the leading end of the label paper 58 and only the web liner 59 is fed between the platen roller 50 and peeling roller 50a. 
The label peeling mechanism also has a web-bending guide 53 positioned in the transportation path whereby the label paper 58 is conveyed between the platen roller 50 and thermal print head 51 in conjunction with clockwise rotation of the platen roller 50. The web-bending guide 53 of the label peeling mechanism causes the label paper 58 to curve through an acute angle to the back (non-label) side of the web. When the label paper 58 passes over the web-bending guide 53 of this label peeling mechanism, the first label 60a adhesively affixed to the front surface of the web liner 59 is unable to follow the transportation path of the web liner 59 and is thus disengaged from the web liner 59. The peeled label 60a is then discharged externally to the printer from the label discharge slot 55. The remaining web liner 59 follows a different transportation path, and the label 60a and web liner 59 are thus separated. This is shown in FIG. 12A.
When this label peeling mechanism is used to peel labels 60a from the web liner 59 and dispense the labels 60a from the label discharge slot 55, the labels 60a are gradually peeled from the leading end thereof in the paper transportation direction by routing the web liner 59 to which the labels 60a are affixed around the web-bending guide 53, and transporting the web liner 59 pauses at a position where a slight portion of the trailing end of the label 60a remains attached to the web liner 59. This is because the label 60a will fall out from the label discharge slot 55 if the label 60a is completely separated from the web liner 59. A peeled label detection sensor 56 can detect the peeled label 60a is in the label discharge slot 55.
When the label paper 58 passes a label detection sensor 57, the label detection sensor 57 detects the trailing end of the first label 60a and the leading end of the next label 60b, and the positions of the labels 60a, 60b can thus be known. The label 60a can thus be stopped at the appropriate position. This operation results in the first label 60a being discharged without being printed.
As shown in FIG. 12B, the label printer then waits for the discharged label 60a to be removed from the web liner 59. The peeled label detection sensor 56 detects when the operator manually removes the label 60a, thus triggering the platen roller 50 to rotate counterclockwise as shown in FIG. 12C to reverse the label paper 58 and position the leading end of the next label 60b on the web liner 59 relative to the thermal print head 51 for printing. Note that the position shown in FIG. 12C is called the “label indexing position.”
The label paper 58 is reversed because advancing the label paper 58 to where the operator can remove the discharged label (to the position shown in FIG. 12A, referred to as the “label peeling position”) positions the leading end of the next label 60b beyond (that is, downstream of) the printing position of the thermal print head 51. If printing then proceeds from this position, the next label 60b will be printed from some middle part of the label. By reversing the label paper 58, however, printing can start from the leading end of the next label 60b (“label indexing position”) when the print data is received.
Whether using the label printer in the peeling mode or using the label printer in the non-peeling mode, the label printer must be mechanically reinitialized (reset) when a new roll is loaded after the last label on a roll is printed and the roll has ended. This involves positioning the leading end of the first label on the new roll next to the printing position of the print head (label indexing process) so that printing can start from the leading end of the label (“label indexing position”).
More particularly, the paper transportation mechanism is driven by a motor to advance the roll paper relative to the print head in this label indexing process. Because the label printer described above is a thermal printer, the roll paper is held between the print head and platen roller, and the platen roller is driven rotationally to convey the roll paper. The platen roller is positioned on the main cover side of the printer, and the print head is positioned inside the printer case.
To replace the roll paper the main cover is opened, the platen roller is released from the print head, and the roll paper is passed between the platen roller and print head. When the main cover is then closed, the roll paper is held between the platen roller and print head, and the roll paper can be transported. The label indexing process must therefore be executed after confirming that the main cover of the label printer is closed.
However, the label printer cannot automatically execute the label indexing process and start printing as soon as print data is received just because the main cover is detected to be in the closed position. This is because in a label printer with an on-board label peeling mechanism the peeling mechanism must be opened after closing the main cover, the roll paper must be loaded into the transportation path used for the peeling mode or the non-peeling mode as desired and the peeling mechanism is then closed to set the roll paper in the desired transportation path. Furthermore, because the operator loads the roll paper, the operator could close the peeling mechanism with the paper accidentally loaded into the wrong transportation path. If the mechanical reset process and printing start with the roll paper loaded into the wrong transportation path, labels are wasted and paper jams or other problems can occur.
A problem with a label printer having a label peeling mechanism as described above is that whether or not the label paper is loaded into the correct transportation path of the peeling mechanism must be confirmed, and the printer cannot be immediately and automatically mechanically reset just because the main cover and peeling mechanism cover are closed.
The label paper 58 used in a printer having a label peeling mechanism has many labels 60a, 60b adhesively affixed to the surface of a continuous web liner 59. When new label paper 58 is loaded into the label peeling mechanism of the printer, a number of labels must be manually removed from the leading end of the label paper 58 so that only the bare web liner 59 is passed around the web-bending guide 53. This is bothersome for the operator and wastes many labels.
Furthermore, if the leading portion of a label affixed to the web liner 59 is positioned to the distal curved portion of the web-bending guide 53 when the label paper is loaded, the leading end of that label disengages from the web liner 59 and exposes the adhesive surface of the label. This adhesive surface can then stick to an internal part of the label printer and interfere with loading the label paper.